The Detection And Parameter Extration Of Frequency Hopping Signal In Cognitive Radio

As the rapid development of the technology of wireless communication, the resource of wireless spectrum becomes more and more deficient. But the improvement in the technology of cognitive radio has more and more made it the solution to this deficiency of spectrum resource, and it could improve the utilization ratio of spectrum and realize the dynamic allocation of spectrum. Frequency Hopping Communication, an important branch of Spread Spectrum Communication, has already been widely used in military and civil communication fields, due to its outstanding characters such as good capacity of resisting disturbance, high utilization ratio of spectrum and good compatibility with Code Division Multiple Access. At the present stage, none of the commonly used spectrum sensing technologies, such as energy detection, cyclostationary detection and matched filter detection, could accurately detect the existence of authorized user who adopts Frequency Hopping Communication as its communication mode. So the research of detection of Frequency Hopping signals and parameter extraction method in cognitive radio is of great value and significance in both theoretical analysis side and engineering realization side.In this paper, according to the attributes of spectrum sensing and Frequency Hopping Communication, a joint detection algorithm, which could be applied to cognitive radio system, based on the signal correlation analysis and time-frequency analysis is put forward. This algorithm is based on the analysis of existing detection methods of Frequency Hopping signals and Frequency Hopping signals’autocorrelation and variability characteristics. Lots of simulation experiments under MATLAB environment and much theoretical analysis have been done, and the algorithm has been optimized to improve detection accuracy and to reduce its complexity. The results of simulation prove that after optimization, dual channel cross-correlation detection method for frequency hopping signals and joint time-frequency analysis method of Short Time Fourier Transform and Wigner-Ville distribution could obviously improve detection performance, effectively reduce complexity of algorithm, and improve its efficiency. They could realize rapid and accurate detection of frequency hopping signals in low SNR environment; thus, they could meet the accurate and real-time requirement of spectrum sensing in cognitive radio. Therefore, they are very feasible in the practical application of cognitive radio.